There is a picture by Paul Klee called 'Angelus Novus.' In it, an angel is depicted who appears as if trying to distance himself from something that he stares at. His eyes and mouth gape wide, his wings are stressed to their limit.
The Angel of History must look this way; he has turned to face the past. Where we see a constant chain of events, he sees only a single catastrophe incessantly piling ruin upon ruin and hurling them at his feet.
He would probably like to stop, waken the dead, and correct the devastation - but a storm is blowing hard from Paradise, and it is so strong he can no longer fold his wings.
While the debris piles toward the heavens before his eyes, the storm drives him incessantly into the Future that he has turned his back upon.
What we call Progress is this storm.